title: Loss of SR-A and CD36 activity reduces atherosclerotic lesion complexity without abrogating foam cell formation in hyperlipidemic mice.
abstract: OBJECTIVE
  The scavenger receptors SR-A and CD36 have been implicated in macrophage foam cell formation during atherogenesis and in the regulation of inflammatory signaling pathways, including those leading to lesional macrophage apoptosis and plaque necrosis. To test the impact of deleting these receptors, we generated Apoe(-/-) mice lacking both SR-A and CD36 and fed them a Western diet for 12 weeks.
  
  
  RESULTS
  We analyzed atheroma in mice, assessing lesion size, foam cell formation, inflammatory gene expression, apoptosis, and necrotic core formation. Aortic root atherosclerosis in Apoe(-/-)Cd36(-/-)Msr1(-/-) mice, as assessed by morphometry, electron microscopy, and immunohistochemistry, showed no decrease in lesion area or in vivo foam cell formation when compared to Apoe(-/-) mice. However, Apoe(-/-)Cd36(-/-)Msr1(-/-) lesions showed reduced expression of inflammatory genes and morphological analysis revealed a approximately 30% decrease in macrophage apoptosis and a striking approximately 50% decrease in plaque necrosis in aortic root lesions of these mice.
  
  
  CONCLUSIONS
  Although targeted deletion of SR-A and CD36 does not abrogate macrophage foam cell formation or substantially reduce atherosclerotic lesion area in Apoe(-/-) mice, loss of these pathways does reduce progression to more advanced necrotic lesions. These data suggest that targeted inhibition of these pathways in vivo may reduce lesional inflammation and promote plaque stability.
authors.affiliation: Lipid Metabolism Unit, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Manning-Tobin
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Moore
authors.forename: Tracie A
authors.initials: TA
authors.lastname: Seimon
authors.forename: Susan A
authors.initials: SA
authors.lastname: Bell
authors.forename: Maia
authors.initials: M
authors.lastname: Sharuk
authors.forename: Jacqueline I
authors.initials: JI
authors.lastname: Alvarez-Leite
authors.forename: Menno P J
authors.initials: MP
authors.lastname: de Winther
authors.forename: Ira
authors.initials: I
authors.lastname: Tabas
authors.forename: Mason W
authors.initials: MW
authors.lastname: Freeman
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency; D050197:Atherosclerosis / Q000235:genetics / Q000473:pathology*; D018955:CD36 Antigens / Q000172:deficiency*; D004195:Disease Models, Animal; D005260:Female; D005487:Foam Cells / Q000473:pathology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006949:Hyperlipidemias / Q000235:genetics / Q000503:physiopathology*; D007249:Inflammation / Q000235:genetics / Q000503:physiopathology; D051379:Mice; D018345:Mice, Knockout; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051117:Scavenger Receptors, Class A / Q000172:deficiency*
chemical_list: D001057:Apolipoproteins E; D018955:CD36 Antigens; C495140:Msr1 protein, mouse; D051117:Scavenger Receptors, Class A; D012313:RNA